The present invention relates to a developing device for a copier, facsimile apparatus, printer or similar image forming apparatus and, more particularly, to a developing device operable with a developer cartridge mounted on, for example, the top of a hopper thereof.
A developing device of the type using a cartridge containing a toner or similar developer is extensively used today. It is a common practice with this type of developing device to provide, for example, a hopper with an air vent and cover it with a filter. When the cartridge is inserted into the hopper, air is forced out through the air vent while the filter catches the toner being entrained by the resulting stream of air. However, the problem with such a conventional device is that when the filter is stopped up by the toner, much time and labor is necessary for a serviceman to clean or replace it. Another conventional developing device is operable with a developer cartridge whose open bottom is hermetically closed by a seal member. This kind of cartridge is provided with a shutter for removing the seal member when the cartridge is mounted on the device. Specifically, after the cartridge has been mounted on a hopper, the shutter is manipulated to remove the seal member and cause a toner or similar developer to drop from the cartridge into the hopper. Such an approach, however, causes another problem that when the shutter is operated, the toner smears the outer periphery of the device around the cartridge and, in addition, the toner existing in the hopper leaks to the outside.